Methods of and apparatus for controlling air gap lengths in core lamination pile-ups



May 26, 1964 Filed Jan. 12, 1961 PRIOR ART R HERINK ETAL METHODS OF AND APPARATUS FOR CONTROLLING AIR GAP LENGTHS IN CORE LAMINATION FILE-UPS 2 Sheets-Sheet l PRIOR ART LVE'N 5755 May 26, 1964 R. HERINK ETAL 3,134,165

METHODS OF AND APPARATUS FOR CONTROLLING AIR GAP LENGTHS IN CORE LAMINATION FILE-UPS Filed Jan. 12, 1961 2 Sheets-Sheet 2 JX/vE/V 'UF E HE'Q/NK :uu. KH'LE' 5 r" TUFRNEJE United States Patent METHODS OF AND APPARATUS FOR CONTROL- LING AIR GAP LENGTHS IN CORE LAMINA- TION PILE-UPS Reinhard Herink, West New York, and Albert W. Kayle,

Bloomfield, N.J., assignors to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Jan. 12, 1961, Ser. No. 82,272 1 Claim. (Cl. 29155.56)

This invention relates to methods of and apparatus for controlling air gap lengths in core lamination pile-ups, particularly for transformer and inductor structures.

In the manufacture of transformer and inductor structures employing core laminations, it is important that the air gaps formed at the opposing inner surfaces of the laminations be of equal lengths. It has been difficult, if not impossible, to accomplish this result in the past with known methods of and apparatus for assembling the laminations and particularly the forcing of the stacks of laminations, which are to compose the cores of various units, to move the opposing inner surfaces toward each other through the application of the conventional force applying means to the opposing outer surfaces of the laminations. It has been found that although the inner surfaces may be accurate, due to the formation of the parts, there exists frequent variations in the distances between opposing outer surfaces of the laminations in each group. Therefore, by the present practice of setting the air gaps, by the application of external pressures or forces through hardened metal surfaces to the outside opposing surfaces of the laminations, such as manually through the aid of a hammer or mechanically with presses or vises, the results would be alignment of the outer surfaces of the laminations and irregular positioning of the inner surfaces forming the air gaps.

Objects of the present invention are highly efiicient and practical methods of and apparatus for controlling air gap lengths between core laminations.

In accordance with the objects, the invention comprises an apparatus, by the aid of which the method may be practiced for controlling air gap lengths in core laminations having companion inner surfaces between which air gaps are to exist and outer opposing surfaces with possible variations in distances therebetween, including the steps of stacking the laminations for a core in their respective order, and applying to the opposing outer surfaces of the laminations forces to move companion inner surfaces of all the laminations toward each other to form like air gaps of sufficient magnitude therebetween of like lengths.

More specifically, in the method, there is an additional step of positioning compliant material on the opposing outer surfaces through which the forces are applied to the outer surfaces of the laminations. In the apparatus, opposing force applying elements are movable between normally open positions, in which a stack of laminations for a core may be disposed therebetween, and force applying positions. In the apparatus, members of compliant material are supported by the elements and positioned to engage opposing outer surfaces of the laminations so that forces applied by the elements to the members will be transferred to the opposing outer surfaces of the laminations regardless of variations in distances between the opposing outer surfaces to form air gaps of like lengths between inner opposing surfaces of the laminations.

Other objects and advantages will be apparent from the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a vertical sectional view of the apparatus in open position Where it has received a stack of laminations;

FIG. 2 is a vertical sectional view of the apparatus in closed position.

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FIGS. 3 and 4 are similar to FIGS. 1 and 2 illustrating the former practice of assembling core laminations; and

FIGS. 5 and 6 are isometric views of different types of laminations used in forming cores.

There are many types of core laminations employed in the forming of cores for transformer and inductor structures, two of these forms being illustrated in FIGS. 5 and 6. Regardless of the forms of laminations, there are always inner opposing surfaces where air gaps are to be formed and opposing outer surfaces against which forces are applied to move the inner opposing surfaces toward each other.

In the illustration of FIG. 5, there are three laminations, many more of which would be used in forming a core. The laminations of this figure are T-shaped laminations 10 and L-shaped laminations 11. The laminations 10 and 11 are punched from strips of material and it is desirable that the laminations be of perfect like structures in their respective groups, but it has been found that this condition does not always exist. Fortunately the inner opposing surfaces 12 of the T-shaped members 10 and 14 of the L-shaped members 11 may be brought into perfect relationship with each other, if the distances between opposing outer surfaces 15 :and 16 were the same. However, this is not always true. Frequently there are variations in this distance between the opposing outer surfaces 15 and 16 which create the disturbance in bringing about equal thickness in the air gaps between the surfaces 12 and 14.

The three laminations, illustrated in FIG. 6, are composed of E-shaped members 18 and I-shaped members 19. In this illustration, the inner surfaces 20 of the E-shaped members 18 are to form air gaps in association with inner surfaces 21 of the I-shaped members 19. In this instance, the opposing outer surfaces are 22 and 23 and, in this instance, the distances between the opposing outer surfaces 22 and 23 may vary creating the disturbance in the possibility of controlling air gaps between the opposing inner surfaces 20 and 211. It should be understood that these variations in distances between the outer opposing surfaces of the various laminations in each stack or group may be very small, but when these small differences in dimensions are placed in the areas of the air gaps, as a result of variations in the positioning of the inner opposing surfaces, there are variations in the electrical characteristics of the unit of which the cores are to be a part.

FIGS. 3 and 4 illustrate former methods and apparatus for setting the laminations in core structures. It should be realized that the illustrations in FIGS. 3 and 4 are greatly exaggerated but this is done for the purpose of illustration. FIG. 3 represents hard metal elements 25 and 26 positioned to engage opposing outer surfaces of a stack of laminations 27 and to force inner opposing surfaces, illustrated in the area of reference numeral 28, toward each other through the application of forces 29 and 30 applied to the elements 25 and 26 to move them toward each other. In FIG. 4, with the elements 25 and 26 in closed positions, the result accomplished is alignment of each group of outer opposing surfaces of the laminations and an irregular positioning of the air gaps between the inner opposing surfaces in the area of reference numeral 28.

To overcome the condition illustrated in FIGS. 3 and 4, the present apparatus, by the aid of which the method may be practiced, includes force applying elements 30' and 31 moved through the aid of forces indicated at 32 and 33 and having members 34 and 35 of compliant material, such as lead, fixed in any suitable manner to the elements 30' and 31, and in this sense, interposed between the force applying elements and the opposing outer surfaces of a stack of laminations 36, for example, a stack of laminations of the type shown in FIG. 6. Therefore, in this illustration, the outer opposing surfaces 22 and 23 will be disposed adjacent the inner surfaces of the members 34 and 35 and when the forces 32 and 33 are applied to the elements 30' and 31, these forces will be transferred to all the outer surfaces 22 and 23, as illustrated in FIG. 2. Here again, the illustration is exaggerated but FIG. 2 illustrates how the opposing outer surfaces with greater distance therebetween may become imbedded in the compliant material of the members 34 and 35, allowing other portions of the members to find the outer opposing surfaces, which are shorter distances apart, and to, in this manner, apply sufficient pressures or forces to all outer opposing surfaces to bring about the result of like lengths in the air gaps between the inner opposing surfaces 20 and 21.

In some instances, the air gaps are created by the actual abutting of the inner opposing surfaces to produce what is called minimum air gap lengths. In other instances, when longer air gaps are desired, spacers such as paper of predetermined thicknesses is disposed between the inner opposing surfaces. Regardless of the dimensions desired for the air gaps between the inner opposing surfaces, these results may be accomplished through the present method and apparatus. Furthermore, the disturbing results from the former methods and apparatus, such as the formation of burrs and lamination grain distortions by the pounding of hard surfaces on the laminations, are eliminated.

It is to be understood that the above described arrangements are simply illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

The method of controlling an air gap between a first group of a plurality of core laminations and a second group of another plurality of core laminations, each group having a companion inner surface between which the air gap is to exist and also having an outer opposing surface with possible variations in distances between the inner and the outer surface comprising:

stacking a plurality of individual laminations for a core one on top of the other into a first group and into a second group, each of said laminations in said groups being freely movable with respect to adjacent laminations, positioning compliant material on the opposing outer surface of each group of laminations, supporting a spacer between the companion inner surfaces of each group of laminations, and applying equal forces to said compliant material to move the laminations individually against the spacer to form a uniform air gap thereat regardless of possible variation in said distances.

References Cited in the file of this patent UNITED STATES PATENTS 906,911 McCullough Dec. 15, 1908 1,206,881 Miller Dec. 5, 1916 1,715,659 Joksch June 4, 1929 2,055,175 Franz Sept. 22, 1936 2,313,689 Waters Mar. 9, 1943 2,319,775 Mittermaier May 18, 1943 2,754,708 Peterson July 17, 1956 2,769,866 Kornei Nov. 6, 1956 2,772,501 Malcom Dec. 4, 1956 2,948,172 Sloboda et al. Aug. 9, 1960 2,991,511 Kornei July 11, 1961 FOREIGN PATENTS 388,891 Great Britain Mar. 9, 1933 

